More evidence that sunlight prevents breast cancer and other cancers—at all ages.

Those who would frighten us away from the sun continue to propagandize that sunlight causes cancer. They sometimes have the decency to say “melanoma” rather than lump all cancers together, but they are dead wrong on that front also; most major cancers, including melanoma, are dramatically reduced by regular sunlight exposure (for references, see the cancer section in my book). There have been so many papers written on the protective effects of sunlight and vitamin D on cancer, that most of the newer papers serve primarily as reinforcement for what is already known. A recent study from Ontario, Canada is a case in point.[1] The researchers determined the amount of time spent outdoors by 3,101 women with breast cancer and compared them with 3,471 women who were cancer-free. The ages of the women was also compared to the risk of cancer to determine the differences in breast-cancer risk during different periods of life. High sunlight exposure was considered to be greater than 21 hours outdoors per week; low exposure was considered to be six hours per week or less.

Among teenagers, high sunlight exposure correlated to reduced risk of breast cancer of 29% compared to those who had the lowest exposure; among those in their 20s and 30s, high sunlight exposure correlated to a reduced risk of 36%; among those in their 40s and 50s, a 26% reduced risk; and among those in their 60s and 70s, a 50% reduced risk.

Other researchers have made similar observations. One group demonstrated that girls who had the greatest exposure to sunlight during the ages of 10-19 had a 35% decreased risk of breast cancer as adults when compared to those who had the least exposure.[2]

And what about prostate cancer? It has been established that men who are in the lowest forth of sunlight exposure have three times the risk of developing prostate cancer compared to those in the highest forth.[3] And young boys who are exposed to lots of sunshine have only about one-fifth the risk of contracting prostate cancer—as adults—when compared to those who have had little sun exposure.[4]

So, are the dermatologists doing us a favor by frightening us away from the sun? You may make your own conclusions. Just remember to avoid burning if you choose to enjoy the health benefits of your solar friend.

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[1] Anderson LN, Cotterchio M, Kirsh VA, Knight JA. Ultraviolet Sunlight Exposure During Adolescence and Adulthood and Breast Cancer Risk: A Population-based Case-Control Study Among Ontario Women. Am J Epidemiol. 2011 Jun 9. [Epub ahead of print]

[2] Knight J. et al. Vitamin D and reduced risk of breast cancer: a population-based case-control study. Cancer Epidemiol Biomarkers Prev 2007;16:422-29.

[3] Moon, S. et al. Ultraviolet radiation: effects on risks of prostate and other internal cancers. Mutat Res 2005; 571:207–219.

[4] Luscombe, C. et al. Exposure to ultraviolet radiation: association with susceptibility and age at presentation with prostate cancer. Lancet 2001;358:641–42.